1. Field of the Invention
The present invention relates generally to a liquid crystal display; particularly, the present invention relates to a mutual capacitance touch sensing apparatus capable of sensing a plurality of data from a conductive thin film sensor simultaneously and avoiding the noise of a liquid crystal panel from influencing the sensing data.
2. Description of the Prior Art
As technology rapidly advances, conventional displays are progressively replaced by thin film transistor liquid crystal displays (TFT LCDs). TFT LCDs are widely used in TVs, flat displays, cell phones, tablet PCs, projectors, and other relevant electronic devices. For TFT LCDs having touch function, touch sensors play an important role among all other modules, and performance of the touch sensor affects the overall performance of LCD.
Generally, the conventional LCD having mutual capacitance touch sensing function includes a display panel, a conductive thin film sensor (e.g. ITO sensor), and a touch control chip, wherein the conductive thin film sensor includes a plurality of sensing lines and a plurality of driving lines, and the touch control chip includes a plurality of pins. The sensing lines are coupled with the pins respectively. When the driving line transmits a driving pulse to couple a small voltage at the sensing line, the touch control chip will sense the coupled voltage and determine according to the magnitude of the coupled voltage whether the conductive thin film sensor is touched.
However, the touch sensing method of the conventional liquid crystal display has some serious defects. For example, the scanning rate is too slow; the noise generated by the display panel seriously influences the operation of the touch control chip. In a worse case, the noise may cause the misjudgment of the location of the touch point. In order to avoid the noise generated by the panel, in some systems, an isolating layer is disposed between the conductive thin film sensor and the panel. However, such an approach inevitably increases the cost and the thickness of the whole device, impairing the mechanical design of device.
Hence, the present invention provides a touch sensing apparatus which can simultaneously sense a plurality of data of the conductive thin film sensor and avoid the sensed data to be influenced by the noise of liquid crystal display panel.